Method and apparatus for skin cancer thermal therapy

ABSTRACT

An apparatus for treatment of soft tissue includes a source of radiation, a handpiece which is adapted to transmit radiation emitted from the source of radiation to a region of soft tissue, resulting in irradiated soft tissue, said handpiece being positioned adjacent to or in contact with said soft tissue region, a grid element adapted to hold at least one temperature sensor in contact with or embedded in said region of soft tissue, and a microprocessor, which converts a signal from the at least one temperature sensor into a measure of damage produced in at least two components of the irradiated soft tissue, said components comprising at least one normal tissue component and at least one malignant, hypertrophic, diseased, or unwanted component.

RELATED APPLICATION

This application is the U.S. National Stage of International ApplicationNo. PCT/US2011/055397, filed Oct. 7, 2011, which designates the U.S.,published in English, and claims the benefit of U.S. ProvisionalApplication No. 61/390,838, filed on Oct. 7, 2010. The entire teachingsof the above application are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Nonmelanoma skin cancer (NMSC) is more common in the United States thanall other types of cancer combined. A recent study of US nationaldatabases has shown a 4.2% yearly average increase in the number of NMSCprocedures in the Medicare population from 1992 to 2006, and a total of3.5 million NMSC procedures performed in 2.2 million Medicare andnon-Medicare patients in 2006 (Rogers H W et al. Arch Dermatol 146(3);283, 2010). Assuming an unchanged rate of increase, five million NMSCprocedures per year will be performed by 2015 in the US. NMSC mostcommonly occurs in people over the age of 50 years, however studies inthe US and Europe have shown a disproportionate increased incidence inwomen under 40 (Christenson L J et al. JAMA 294; 681, 2005,Birch-Johansen et al. Int J Cancer Apr. 19, 2010), raising concerns ofan even higher number of patients in future, and resultant increasedmorbidity and economic burden.

NMSC includes both squamous cell carcinoma (SCC) and basal cellcarcinoma (BCC), and is caused by ultraviolet (UV)-induced mutations inepidermal cells. Seventy-five to eighty percent of new cases of NMSCeach year are BCC (Tierney E P, Hanke C W. J Drugs Dermatol 8; 914-922,2009). A recent study has shown that BCC arise from keratinocytes of theinterfollicular epidermis (Youssef K K et al. Nat Cell Biol 12; 299-305,2010). BCC appear as different histologic subtypes, including nodular(45.9% of all BCC), superficial (25.9%), infiltrative (16.0%), andmicronodular (9.1%), as well as other and mixed subtypes (Raasch B A etal. Br J Dermatol 155; 401-7, 2006) Infiltrative and micronodular BCCare classified as “high risk” tumors, as are nodular tumors of themidface or ear, and large or recurrent tumors. Risk in the context ofBCC refers to aggressiveness or likelihood of spread or recurrence aftertreatment, rather than mortality. BCC of any type or location has a verylow probability of metastasis; however it is locally destructive, and ifleft untreated or treated incompletely may become deeply and/or widelyinvasive of surrounding skin and subcutaneous tissue. With the exceptionof superficial BCC (sBCC), which are most common on the trunk orextremities, the majority of BCC occur on the face. BCC and other NMSChave their highest incidence in people of European ethnicity, but alsooccur in Asian populations, and with increasing incidence (Kim H S etal. J Korean Med Sci 25; 924-9, 2010).

The first goal in treatment of BCC, as in any cancer treatment, is thecomplete eradication of tumor cells; the second objective is sparingsurrounding normal tissue required for good cosmesis and function.Surgery and destructive methods such as cryosurgery, andelectrodessication and curettage (EDC), are the mainstays for treatmentof NMSC, and with those methods complete tumor cell eradicationnecessitates damage to normal tissue.

Of all BCC surgeries, Mohs micrographic surgery is the mosttissue-sparing. It is also the most reliably effective in removing allmalignant cells associated with the lesion, and has a 5 year recurrencerate of only 1% for primary tumors (Muller F M et al. Dermatol Surg 35;1349-1354, 2009). The cost of Mohs surgery depends on the number ofstages or levels that are subjected to histological analysis for mappingof the tumor and the complexity of the repair needed for the resultingskin defect. Average costs of Mohs surgery for treatment of BCC on thecheek are $1263 (Rogers H W, Coldiron B M. J Am Acad Dermatol 61;96-103, 2009). Larger, deeper lesions or lesions in difficult anatomiclocations can cost substantially more. The surgical wound can beextensive and often requires reconstruction using flaps or fullthickness skin grafts. The number of physicians receiving formaltraining in Mohs surgery has increased substantially in the past decade,and 25% of all dermatologists now perform this procedure (Tierney E P etal. Derm Surg 35; 413-9, 2009).

Traditional surgical excision with immediate or delayed repair of thesurgical defect is another standard treatment of BCC. Typically, a 4 mmmargin of normal-appearing skin is excised with the tumor. A comparisonof surgical excision with Mohs has shown that excision leaves a 60%larger surgical defect (Muller F M, et al. Dermatol Surg 35; 1349-1354,2009). Remarkably, retrospective analysis has shown that 14% of BCC areincompletely excised (Malik V, et al. J Plast Reconstr Surg Aesth Surg,2010). Because of the difficulty in determining the subsurface spreadand depth of the tumor and the competing need to preserve healthy,uninvolved skin tissue, surgical excision has higher recurrence ratesthan Mohs surgery. The 5 year recurrence rate for primary BCC followingsurgical excision is approximately 5% (Thissen M R et al. Arch Dermatol135; 177-183, 1999). Excision of a BCC on the cheek with permanentmargins and immediate or delayed repair is estimated to cost on average$1006 and $1170, respectively (Rogers H W, Coldiron B M. J Am AcadDermatol 61; 96-103, 2009).

The least costly methods of treating BCC are cryosurgery and EDC.Cryosurgery is commonly used to treat superficial BCC on the trunk orextremities. Because it is nonselectively destructive, significantscarring, skin texture changes, and hypopigmentation commonly result. Aswith EDC there is no opportunity to examine the margins ofnormal-appearing skin left behind after surgery, and so it is not apreferred treatment for BCC of aggressive subtypes or on locationsassociated with high risk of recurrence. The estimated average cost ofEDC for BCC on the cheek and arm is $471 and $392, respectively. Fiveyear recurrence rates for cryosurgery and EDC are 7.5 and 7.7%,respectively (Tierney E P, Hanke C W. J Drugs Dermatol 8; 914-922,2009). Recurrences after cryosurgery or EDC are typically treated withMohs surgery.

Although excision, Mohs, EDC and cryosurgery are effective in treatingNMSC, there has been a long-standing interest in alternatives that wouldprovide better cosmetic and functional results, and allow the patient toavoid invasive and destructive surgery. As early as the 1960's, a numberof chemotherapeutic and immunotherapeutic drugs were tested (Williams AC, Klein E. Cancer 25; 450-462, 1970). Topically appliedchemotherapeutic drugs produced inconsistent results on BCC, with sideeffects including blistering, crusting, and dermatitis. Consequently,topical chemotherapeutic drugs were largely abandoned as treatmentalternatives. The exception has been 5-fluorouracil (5FU, Efudex®,Valeant Pharmaceuticals International, Aliso Viejo, Calif.) which hasbecome a widely-used, standard treatment for actinic keratoses (AKs,epidermal precursor lesions for SCC) and is approved by FDA fortreatment of sBCC when conventional treatments are impractical.Histologic cure rates of 90% have been reported for sBCC treated over aperiod of up to 12 weeks with 5FU (Gross K et al. Derm Surg 33; 433-9,2007). 5FU treatment of BCC other than the superficial type may resultin apparent clinical cure with tumor persisting in the deeper dermis,potentially resulting in recurrence with subclinical spread (Lee S etal. Drugs 67; 915-934, 2007).

The early immune response modifiers tested showed efficacy forsuperficial skin tumors, and a newer drug imiquimod (Aldara®, GracewayPharmaceuticals, Bristol, Tenn.) was introduced in the past decade (LoveW E, et al. Arch Dermatol 145; 1431-1438, 2009). Therapy involvesapplication five times a week for six weeks. Imiquimod is currentlyapproved by FDA only for treatment of superficial BCC less than 2 cm indiameter and only on the trunk, neck, or extremities. When imiquimod hasbeen used to treat nodular or micronodular BCC, it has been found thatclearance of the tumor in the upper layers of the skin can mask residualdeeper involvement and growth, which may be the result of poor exposureof the deeper tumor to the topical drug (Sukai S A, et al. Derm Surg 35;1831, 2009).

Both imiquimod and 5FU therapies require patient adherence to lengthytreatment regimes, and both have frequent adverse effects. Based on areview of published data, it has been recommended that use of imiquimodand 5FU be limited to patients with small superficial BCC in low riskanatomic locations when more effective surgical or destructiveprocedures cannot be used (Love W E et al. Arch Dermatol 145; 1431-8,2009).

Treatment of NMSC including BCC with lesional and perilesionalinterferon injections avoids the problem of limited depth of drugpenetration implicated in 5FU and imiquimod failures when treatingnon-superficial tumors. However, the injected interferon has a highincidence of systemic adverse effects and administration may requiremany office visits over a period of several weeks. Intralesionalinjections of interferons or other agents are rarely used to treat NMSC.

Photodynamic therapy (PDT), which involves activation of aphotosensitizing drug with light, has been studied for many years fortreatment of BCC. Effective PDT requires that both drug and light fullypenetrate the tumor. PDT using the topically-applied photosensitizeraminolevulinic acid or its derivatives is approved for treatment ofsBCC. A recent multi-site study reported short term results in the morecommon nodular BCC; patients received two to four PDT sessions precededby debridement and debulking of the tumor to facilitate penetration ofthe drug. Histologically verified complete response was 73% versus 27%for a placebo control group at 6 months. (Foley P, et al. Int J Dermatol48; 1236, 2009). Pain is a significant side effect of PDT for skincancer.

All of the above mentioned nonsurgical alternative treatments for NMSCthat involve topical agents applied to the skinsurface—chemotherapeutic, immunotherapeutic or photodynamic drugs—haveas a major limitation the inability to reliably treat BCC other thansuperficial type, which comprise only about 20% of all BCC. Otherdrawbacks are multiple treatment visits and prolonged treatment regimes.Although the cosmetic and functional outcomes of these alternativetherapies are frequently superior to those of surgical or destructiveprocedures, the advantage of a traditional surgical procedure thatreliably removes or destroys the tumor in a single office visit issufficient that the alternatives currently have a minor role intreatment of BCC and other NMSC.

The potential use of laser radiation to eradicate skin cancer has beenof long-standing interest, with first reports appearing only a few yearsafter the laser was invented. Near infrared (NIR) and infrared (IR)laser treatment of NMSC is based on absorption of radiation by water,the main component of soft tissue including skin and tumor tissue. TheCO₂ laser operates at an IR wavelength (1.06 μm) that is very stronglyabsorbed by water, and therefore has limited depth of penetration insoft tissue. The CO₂ laser in pulsed or repetitively scanned mode can beused to vaporize superficial skin tumors layer by layer. Larger, deeper,and infiltrative tumors are not effectively eradicated and there islittle advantage in treatment of even superficial lesions with thisalternative destructive technique (Prstojevich S J and Nierzwicki B J,Oral Maxillofacial Surg Clin N Am 17; 147, 2005). The CO₂ laser is notrecommended for routine treatment of skin cancer (Hruza G J, DermatolClin 20; 147, 2002).

NIR Nd:YAG lasers operating at 1064 nm penetrate much deeper in softtissue due to the weaker absorption by water at this wavelength, andhave been used to coagulate rather than vaporize skin tumors. Nd:YAGlaser treatment of NMSC results in delayed wound healing, scarring, andunacceptably high recurrence rates (Landthaler M, et al. Recent ResCancer Res 130; 417, 1995). Burn-like scars are reported to beinevitable following treatment of BCC or other skin cancers with the1064 nm Nd:YAG laser (Karrer S, et al., Am J Clin Dermatol 2; 229,2001). When using the Nd:YAG laser both the tumor and the surroundingnormal skin absorb the NIR radiation and are heated, and both of thesecomponents are typically coagulated with the objective of eradicatingall tumor cells. This thermal laser technique is “blind” as there is nomeans of intraoperatively or postoperatively assessing tumor celleradication, other than by tumor recurrence. Recently, Russianresearchers described the use of a high power pulsed Nd:YAG laser fortreatment of a large series of patients with NMSC; treatment parameterswere described as causing total destruction of the tumor and coagulativenecrosis of adjacent normal tissue, healing with crusting andreepithelialization, with the end result of a smooth scar at thetreatment site (Moskalik K et al., Photomed Laser Surg 27; 345, 2009). Asmaller study reported using a continuous wave Nd:YAG laser in up to 4treatment sessions in 37 patients (El-Tonsy M H et al., DermatologyOnline Journal 10(2); 3, 2004). Treatments involved using a thermocoupleon the skin surface away from direct exposure to the laser beam tomonitor surface temperature, and irradiating the tumor site with thelaser to maintain a temperature of 45° C. for 1 minute. Superficialerosion and crusting were seen as normal consequences of the treatment,which resulted in permanent scarring in 11% of patients, and 3%recurrence at 3-5 years followup. Other limitations of the El-Tonsymethod include the unknown temperature at the actual locations of tumorcells below the skin surface, and the lack of any means of correlatingtreatment time and temperature (surface or at depth) with damage totumor cells or surrounding normal skin. Other researchers withexperience with the Nd:YAG laser do not recommend its routine use fortreatment of NMSC (Raulin C, Karsai S, Schmitt L, in Laser and IPLTechnology in Dermatology and Aesthetic Medicine, pp 165-175, Springer,2011).

Thus, at present, although ablative IR and thermal NIR lasers have beenin the surgical armamentarium of dermatologists for many decades, theyhave not been successfully adapted for standard treatment of BCC andother NMSC.

Visible wavelength vascular targeting lasers have been a recent subjectof evaluation for NMSC treatment (Raulin C, Karsai S, Schmitt L, inLaser and IPL Technology in Dermatology and Aesthetic Medicine, pp165-175, Springer, 2011). The present inventor first reported the use ofthe 585 nm pulsed dye laser (PDL) for BCC treatment (Beutner K R, GeisseJ K, Alexander J, McMillan K Lasers Surg Med Suppl 14; 22, 2002). ThePDL was evaluated as a means of treating BCC by selective eradication ofthe blood supply on which the tumor cells depended. This study wasfollowed by others (Allison K P, Kiernan M N, Waters R A, Clement R M,Lasers Med Sci 18; 125-6, 2003, Campolini P, Troiano M, Bonan P,Cannarozzo G, Lotti T. Dermatol Ther 21; 402-405, 2008, Shah S M,Konnikov N, Duncan L M, Tannous Z S, Lasers Surg Med 41; 417-422, 2009).These studies demonstrated the ability of PDL treatment to eradicatesome BCC of different histologic types, and cosmetic results areexcellent compared to the standard nonselectively destructivetreatments. Several treatment sessions are typically required forsuccessful eradication, and not all lesions respond completely. RecentlyIbrahimi et al. reported the use of a 755 nm flashlamp-pumpedalexandrite laser to treat basal cell carcinoma in Gorlin's syndrome.Laser-induced microvascular injury was seen at depths to thesubcutaneous tissue however treatment led to hypopigmentation andscarring (Ibrahimi O A, et al. Lasers Surg Med 43; 68, 2011). Afundamental difficulty with the photothermal vascular targetingapproach, using any wavelength or combination of wavelengthspreferentially absorbed by blood, is that only a portion of vessels inthe irradiated volume are coagulated at fluences below the threshold fordamage to nonvascular structures and scar formation; therefore, tumoreradication requires multiple treatments even in smaller or superficialtumors. To address this problem, the present inventor has described anapparatus and method for using vascular targeting lasers to treat NMSCby a combined process of targeting tumor vasculature and increasing theexposure of tumor cells to topical anticancer drugs by modification ofskin permeability (McMillan K, WO/2010/102099A1). Deeper, thicker andmore extensive tumors are challenging due to difficulties in selectivetargeting of microvasculature at depth in the dermis using vascularlasers. At present, vascular-targeting lasers including PDL andalexandrite are not yet routine alternatives to surgical excision fortreatment of NMSC.

For a nonsurgical treatment for NMSC to become a routine andadvantageous alternative for treatment of commonly presenting tumors andnot only sBBC, it should have sufficient efficacy in eradicating tumorcells at depth within the tissue that histological examination oftreatment margins (as in surgical excision or Mohs surgery) isunnecessary. This significant challenge is made more difficult by thevariety of different histologic subtypes of BCC having differentpatterns of cellular and vascular growth, and the possibility ofsubsurface lateral and deep extension beyond the clinically evidentportion. Furthermore, skin that is the tumor environment itself variesin thickness: neck, nasal tip, and forehead skin has thickness (combineddermal and epidermal) of 0.5, 1.2, and 1.0 mm, respectively (Ha R Y, etal. Plast Reconstr Surg 115; 1769, 2005), and skin on the back, dorsalaspect of forearm, and lateral aspect of the leg has thickness 2.5, 1.1,and 1.3 mm, respectively (Tan C Y et al. Br J Dermatol 106; 657, 1982).Also, the thickness of subcutaneous adipose tissue and/or fasciaunderlying the dermis is highly variable with anatomic location andbetween patients.

At present, with the number of BCC and other NMSC requiring treatmentvery high and increasing, there is a pressing need for a new treatmentthat (1) is highly effective, (2) provides excellent cosmetic results,(3) can be rapidly and easily performed by the physician, (4) is lesscostly than surgical excision or Mohs surgery, and (5) is not limited tosuperficial, primary tumors.

SUMMARY OF THE INVENTION

The invention generally is directed to treatment of soft tissue with asource of radiation, resulting in irradiated soft tissue, measuring thetemperature in at least one location within the region of soft tissue,and converting the temperature in the at least one location within theregion of soft tissue into a measure of damage produced in at least twocomponents of the irradiated soft tissue, the components comprising atleast one normal tissue component and at least one malignant,hypertrophic, diseased, or unwanted component.

In one embodiment, an apparatus for treatment of soft tissue includes asource of radiation, a handpiece which is adapted to transmit radiationemitted from the source of radiation to a region of soft tissue,resulting in irradiated soft tissue, said handpiece being positionedadjacent to or in contact with said soft tissue region, a grid elementadapted to hold at least one temperature sensor in contact with orembedded in said region of soft tissue, and a microprocessor, whichconverts a signal from the at least one temperature sensor into ameasure of damage produced in at least two components of the irradiatedsoft tissue, said components comprising at least one normal tissuecomponent and at least one malignant, hypertrophic, diseased, orunwanted component. The at least one normal tissue component can becollagen. The at least one malignant, hypertrophic, diseased, orunwanted component can be tumor cells. In some embodiments, the at leastone normal tissue component can be dermal collagen, and the at least onemalignant, hypertrophic, diseased, or unwanted component can be skincancer cells. The source of radiation can be a coherent or incoherentsource emitting radiation in a range between about 700 nm and about 1310nm, such as in a range between about 1100 nm and about 1310 nm, or in arange between about 1100 nm and about 1140 nm. The grid element can beattached to the handpiece. In some embodiments, the grid element can beremovably attached to the handpiece. In certain embodiments, the gridelement can be disposable. The grid element can be adapted to hold atleast two temperature sensors embedded at least two different depths inthe irradiated soft tissue. The at least one temperature sensor can be athermocouple or a thermistor. In some embodiments, the thermocouple orthermistor can be contained within a needle having a proximal end and adistal end, such that the proximal end is affixed to the grid elementand the distal end is embedded in the irradiated soft tissue. Themeasure of thermal damage can be the Arrhenius damage integral. In someembodiments, the handpiece can include a cooling element for cooling theregion of soft tissue for at least a portion of the time that the atleast one temperature sensor is in contact with or embedded in said softtissue. In certain embodiments, the apparatus can further include adisplay unit, whereby the measure of thermal damage produced in at leasttwo components of the irradiated tissue is displayed for at least aportion of the time that the at least one temperature sensor is incontact with or embedded in said soft tissue.

In another embodiment, an apparatus for treatment of soft tissueincludes a source of radiation adapted to irradiate a region of softtissue, a means of measuring temperature in at least one location withinsaid region of soft tissue before, during, and after irradiation, and ameans of converting the temperature in the at least one location withinsaid region of soft tissue into a measure of damage produced in at leasttwo components of the irradiated soft tissue, said components comprisingat least one normal tissue component and at least one malignant,hypertrophic, diseased, or unwanted component.

In yet another embodiment, an apparatus for treatment of soft tissueincludes a source of radiation, a handpiece which is adapted to transmitradiation emitted from the source of radiation to a region of softtissue, when said handpiece positioned adjacent to or in contact withsaid soft tissue region, a means of measuring temperature in at leastone location within said region of soft tissue, and a means ofconverting the temperature in the at least one location within saidregion of soft tissue into a measure of damage produced in at least twocomponents of the irradiated soft tissue, said components comprising atleast one normal tissue component and at least one malignant,hypertrophic, diseased, or unwanted component. The handpiece can includea cooling element for cooling the region of soft tissue.

In still another embodiment, a method of heating a biological tissue byapplication of radiation, the tissue comprising at least one normalcomponent and at least one abnormal, diseased, hypertrophic, malignant,or otherwise unwanted component, includes irradiating a treatment regionof the tissue to cause thermal injury to the at least one normalcomponent and the at least one unwanted component, monitoringaccumulation of thermal injury during irradiation to the at least onenormal component and the at least one unwanted component, and endingirradiation when the at least one unwanted component has beensubstantially injured by heat. In some embodiments, ending irradiationoccurs when (a) the at least one unwanted component has beensubstantially injured by heat, and (b) the at least one normal componentis substantially uninjured by heat. Monitoring the accumulation ofthermal injury can include measuring tissue temperature as a function oftime before, during, and after irradiation at one or more locationswithin the tissue. Alternatively, monitoring the accumulation of thermalinjury can include simultaneously (a) measuring tissue temperature as afunction of time before and during application of radiation, and (b)calculating the tissue cooling rate and time required for the tissue tocool to a temperature at which accumulation of thermal injurysubstantially ceases, at one or more locations within the tissue.Irradiating the treatment region can include applying radiation at awavelength within a range of about 1100 nm to about 1310 nm, such as awavelength within a range of about 1100 nm to about 1140 nm, in aspecific embodiment a wavelength of about 1125 nm.

In another embodiment, the method of treating a region of skin includesirradiating the region of skin with a light source adapted to producepreferential injury to blood vessels of a dermal region, and irradiatingthe region of skin with radiation at a wavelength within a range ofabout 1100 nm to about 1310 nm. In some embodiments, the method caninclude waiting for formation of purpura and/or a significant reductionin dermal blood flow after irradiating the region of skin with the lightsource to produce preferential injury to blood vessels of a dermalregion and before irradiating the region of skin with radiation at awavelength within a range of about 1100 nm to about 1310 nm. Someembodiments can further include applying a topical agent to the skinbefore irradiating the region of skin with radiation at the wavelengthwithin the range of about 1100 nm to about 1310 nm.

A highly advantageous nonsurgical treatment for NMSC should be able toeradicate malignant cells of superficial tumors in or near the epidermisas well as deeper tumors extending to the reticular dermis orsubcutaneous tissue layers, regardless of skin thickness, withoutcausing significant injury to normal skin structures resulting inscarring and poor cosmetic outcomes. Most advantageously, the newtreatment is noninvasive or minimally invasive, can be performed in asingle session in a physician's office, and is more effective thansurgical excision or comparable in efficacy to Mohs surgery.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particulardescription of example embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingembodiments of the present invention.

FIGS. 1A-D are microscopic photographs of examples of superficial,nodular, micronodular, and infiltrative BCC tumors.

FIGS. 2A-C are contour plots of the temperature within the skin at theend of 14 J/cm², 16 J/cm², and 18 J/cm² pulses from a 1450 nm laser.FIG. 2D shows the damage integral Ω as a function of depth, for thethree different fluences.

FIG. 3 is a contour plot of temperature within the skin at the end of a10 W irradiation with an 1125 nm laser.

FIG. 4A shows, as an unshaded region, wavelengths corresponding to adepth of penetration in skin of at least 3 mm FIG. 4B shows, as anunshaded region, wavelengths where blood absorption relatively lowcompared to water. FIG. 4C shows, as an unshaded region, wavelengthscorresponding to both deep penetration and low blood absorption. FIG. 4Dshows highly advantageous wavelengths of deeper penetration.

FIG. 5 is a contour plot of temperature within the skin at the end of a20 W irradiation with an 1125 nm laser.

FIGS. 6A and 6B are semi-schematic side and end views, respectively, ofa handpiece 1 of the invention.

FIGS. 7A and 7B are semi-schematic views of a grid element 9 of theinvention.

FIG. 8 is a schematic view of an apparatus 100 of the invention.

FIG. 9 is a treatment schema of the invention, using laser thermaltherapy.

FIG. 10. is a semi-schematic view of a grid element 9 of the invention,with permeability needles 9 g and sensor needles 10.

FIG. 11 is a treatment schema of the invention, using laser thermaltherapy and a topical drug.

FIG. 12 is a contour plot of temperature within the skin at the end of a4 J/cm² pulsed dye laser pulse, showing vascular damage in the upperdermis.

FIG. 13 is a contour plot of temperature within the skin at the end of a9 J/cm² pulsed dye laser pulse, showing more extensive vascular damage.

FIG. 14 is shows the absorption spectrum of coagulated blood and itsconstituents.

FIG. 15 depicts an advantageous treatment wavelength.

FIG. 16 is a treatment schema of the invention, using laser thermaltherapy and vascular laser treatment.

FIG. 17 is a treatment schema of the invention, using vascular lasertreatment and topical anesthetic administration, followed by laserthermal therapy.

FIG. 18 is a schematic representation of the zones of skin affected by avascular laser (dashed outline), thermal laser (solid outline), and both(diagonal hash marks).

FIG. 19 is a treatment schema of the invention, using vascular lasertreatment and topical anesthetic administration, followed by laserthermal therapy, followed by topical anticancer drug administration.

FIG. 20 is a schematic representation of an ablation element 30 of theinvention.

FIG. 21 is a photograph showing features of the substrate 31 of anablation element 30.

FIG. 22 is a schematic view of an apparatus 100 of the invention, inwhich a thermal laser 120 is combined with a vascular laser 150.

FIG. 23 is a treatment schema of the invention, using vascular lasertreatment and topical anticancer drug application, followed by laserthermal therapy.

DETAILED DESCRIPTION OF THE INVENTION

A description of example embodiments of the invention follows.

Embodiments of the present invention address, by means of noveltechnology and novel methodology, the current, long-standing problemsand inadequacies of skin cancer treatments. The present invention may beused to treat BCC, SCC, as well as other malignancies, premalignancies,and unwanted structures or lesions of the skin, mucosa, epitheliallayers, or other soft tissues elsewhere in the human body. An importantaspect of the present invention is the capability of effectivelyeradicating malignant cells without significant normal tissuedestruction, for the most advantageous clinical outcome.

To facilitate understanding of the invention, microscopic photographs ofexamples of BCC tumors are shown in FIGS. 1A-D (original photographsfrom Campbell J B, “Normal Microanatomy: Vertical and Horizontal”, andCrowson A N and Garcia C, “Basal Cell Carcinoma: Vertical andHorizontal” in Mohs Surgery and Histopathology: Beyond the Fundamentals,Eds.: K Gross and H K Steinman, Cambridge University Press, 2009, pp85-108). In FIGS. 1A-D, stars are used to mark locations of tumor cellswithin the original photographs.

FIG. 1A is an example of a superficial BCC tumor (sBCC). The tumor cellslie in close proximity to the affected epidermis. An advantageoustreatment of sBCC will effectively eradicate tumor cells very close tothe skin surface, with minimal damage to surrounding normal, unaffectedepidermis that would lead to scarring, or skin texture or pigmentationchanges.

FIG. 1B is an example of a nodular BCC (nBCC). The lobules of the tumormay extend from the epidermis deep into the dermis. Effectiveeradication of nBCC requires treatment at depth as well as close to theskin surface. Advantageous treatment of nBCC will produce minimal damageto surrounding normal, unaffected epidermis or dermis, which would leadto scarring, or skin texture or pigmentation changes.

FIG. 1C is an example of a micronodular BCC (mnBCC). In mnBCC, the tumorlobules are smaller and widely dispersed, and may extend deep into thedermis and subcutaneous adipose tissue. Effective eradication of mnBCCrequires treatment at depth as well as close to the skin surface, andover an extensive volume where micronodules may reside within skin.

FIG. 1D is an example of an infiltrative BCC (iBCC). iBCC comprise smalltumor cords extending deeply into the reticular dermis and subcutaneoustissue. Effective eradication of iBCC requires treatment at depth aswell as close to the skin surface, over an extensive volume where tumorcords may reside within skin, and complete killing of cells of thisaggressive subtype of BCC. As with all other tumor subtypes,advantageous treatment of iBCC will produce minimal damage tosurrounding normal, unaffected epidermis or dermis, which would lead toscarring, or skin texture or pigmentation changes.

These BCC subtypes often exist in combination within the same lesion,and other terminology may be used for these and other subtypes. However,for the purpose of illustrating aspects of the problem of treating BCC,the subtypes shown in FIGS. 1A-D are useful.

In addition to the variations in the different histologic subtypes, BCCmay also vary in vascularity, with some tumors having a higher densityof blood vessels than others, either within the tumor itself or at thetumor periphery. Significant variability exists in the depth and widthof extent of BCC in the skin, depending on subtype, aggressiveness,anatomic location, and duration of growth. It is often difficult orimpossible to determine the true extent of a BCC from the appearance ofthe lesion on the skin surface, or from a superficial biopsy.

As may be appreciated, an advantageous method of treating BCC requires asubstantially selective effect on the malignant cells throughout theskin, with sufficient sparing of surrounding normal tissue that theprocedure results in preservation of good form and function of the skintissue.

A finding of the present invention is that tumor cells can beirreversibly injured or killed by heating conditions that will produceless damage to the most relevant component of the skin tissue thatcontains said tumor cells. Herein, heating conditions are described bytemperature as a function of spatial location within the tissue volumeand as a function of time before, during, and after treatment.Temperature as a function of time and spatial location will be referredto herein as the “thermal history” at that location. In advantageousembodiments of the invention, a skin cancer is subjected over itsentirety to a thermal history that produces an injury to the malignantcells that is at or above the threshold of injury, with concomitantproduction of an injury to the normal skin components surrounding orinterspersed with said malignant cells that is below the threshold ofinjury. In advantageous embodiments of the invention, the tumor cellswill be substantially and irreversibly injured, and the surroundingnormal skin tissue will not be so injured as to produce cosmetically orfunctionally significant scarring.

Rather than comparing the tumor cell thermal injury threshold to normalskin tissue cell thermal injury threshold, in the finding describedherein, tumor cell thermal injury threshold is compared to the thresholdfor thermal injury to collagen fibers. Whereas most normal tissues ofthe body are made up of living cells in close adherence to one another,dermis and other subepithelial tissue is composed mainly of structuralprotein fibers, specifically collagen, with living cells being a minorcomponent. According to the present invention, a comparison of tumorcell injury threshold to normal skin cell injury threshold is lessimportant than a comparison of tumor cell injury threshold to thethreshold for collagen denaturation.

A comparison between the thermal injury thresholds for collagen and fortumor cells has not previously been made, although in the finding of thepresent invention it is fundamental to the development of anadvantageous thermal therapy for treatment of skin cancer. According tothe present invention, the threshold for significant injury to normalskin components in the vicinity of malignant cells in a skin tumor isrelated to the Arrhenius rate parameters for thermal injury to collagen.Collagen is an extracellular matrix protein that makes up about 80% ofthe dry weight of the dermis, and takes the form of coiled fibers thatgive form, elasticity and resilience to the skin. Under sufficientlyaggressive heating conditions, the intermolecular hydrogen bonds thatgive the collagen its three dimensional structure are broken, and thefibers will contract in a process referred to as denaturation. Somedenatured collagen in the dermis can be removed as part of the processof healing after thermal injury, but if the collagen denaturation issufficiently complete the result is coagulative necrosis, wherein thehealing process cannot lead to resorption of the volume of damagedcollagen. The result of excessive thermal injury to the dermis may be ahard, shrunken mass of denatured collagen that the body is unable toabsorb, that is a scar, and which has a disadvantageous cosmetic and/orfunctional result.

Using the Arrhenius rate model, thermal injury can be calculated usingthe following equation:Ω(δ)=ln [C(0)/C(δ)]=∫₀ ^(δ) Ae ^(−E/RT) dt  Eq. 1where ‘δ’ is the total treatment time, ‘C’ is the concentration ofnative (undamaged) tissue, tissue component or cells under study beforetreatment or at time δ, and ‘A’ and ‘E’ are the Arrhenius rateparameters for the tissue component or cells. T is the absolutetemperature and R is the universal gas constant. Ω is a quantificationof the amount of thermal injury that occurs during treatment. A value ofΩ=1.0 is conventionally defined as the threshold for injury (see forexample J. Pearce and S. Thomsen, “Rate Process Analysis of ThermalDamage,” in Optical-Thermal Response of Laser-Irradiated Tissue, eds. A.J. Welch and M. J. C. van Gernert, Plenum Press, NY 1995, p. 568). Ω=1.0corresponds to C(δ)/C(0)=0.368, or 37% undamaged tissue remaining at theend of treatment.

The approach taken in the discovery described herein is as follows:first, the value of Ω corresponding to the upper limit of clinicallyacceptable damage to dermis is found by a study of Ω for awell-established, existing commercial medical laser for which extensiveclinical experience is available. (This approach does not start with theconventional definition of Ω=1.0, rather, the value of Ω correspondingto the threshold for actual clinically apparent injury, i.e. scarring ofthe skin or textural or pigmentation changes, is determined on the basisof extensive clinical experience.) Secondly, for a light source of thepresent invention having a wavelength that is advantageous for treatmentof skin cancer, the Ω value found in the first step is used to identifytreatment parameters that can be safely applied to dermis using the new,advantageous wavelength. Thirdly, the response of tumor cells to thesetreatment parameters at this new laser wavelength is determined. In thisway it can be shown that according to the present invention, tumor cellsin the skin can be injured and killed using laser parameters that aresubstantially sparing of normal dermis.

The 1450 nm diode laser with surface cryogen spray cooling (Smoothbeam,Candela Corporation, Wayland Mass.) is well known for treatment of acne,acne scars, wrinkles, and other benign dermatologic conditions, havingbeen in clinical use for approximately 10 years. The Smoothbeam laserproduces pulses in the range of 160 to 220 milliseconds divided intofour equal micropulses separated with three cooling sprays of 134acryogen. This laser is routinely used at fluences of 12 to 14 J/cm² witha 6 mm diameter irradiated spot. A fluence of 16 J/cm² is the maximumrecommended for treatment of acne, acne scars and wrinkles. Theinteraction of this laser with skin can be modeled using the Monte Carlomethod with heat transfer analysis, and optical and thermal propertiesof the skin known in the art.

FIGS. 2A-C are contour plots of the temperature within skin at the endof a 14 J/cm², 16 J/cm², and 18 J/cm² pulse respectively. (The latterfluence, 18 J/cm², is above the recommended dosage and may causescarring or other untoward effects, based on Smoothbeam clinical laserexperience.) In each case the laser spot size on the skin surface is 6mm, and the cryogen cooling is the same. It can be seen that the regionof maximum heating is approximately 150 to 200 microns below the skinsurface. The maximum temperature varies by only about 20° C. with thethree different laser fluences modeled here. FIGS. 2A-C show thetemperature contours at the end of the laser pulse, however the modelcalculations provide temperature at any point within the skin and at anypoint in time during and after laser treatment.

According to Eq. 1, the amount of injury depends on both time andtemperature (the thermal history), and the Arrhenius parameters A and Especific for the tissue component or cell type under consideration. Asnoted previously, normal skin tissue thermal injury is characterizedherein by the amount of heat-induced collagen denaturation. A and Evalues for dermal collagen denaturation are well known in the art.Herein, A is taken as 1.606×10⁴⁵ s⁻¹ and E is 3.06×10⁵ J/mol⁻¹.

Using these Arrhenius parameters for collagen denaturation, Eq. 1 andthe mathematical model calculations are then combined to find Ω valuesafter irradiation with the three specific Smoothbeam laser treatmentfluences. The model calculations comprise Monte Carlo simulations ofphoton transport, followed by heat transfer analysis. FIG. 2D showsdamage Ω as a function of depth in the skin tissue, at the center of a 6mm diameter Smoothbeam laser beam. This calculation shows that themaximum damage Ω is 0.12 (11% collagen denaturation), 1.2 (70% collagendenaturation), and 11 (100% collagen denaturation), respectively, for 14J/cm², 16 J/cm², and 18 J/cm² pulses. These calculations indicate that arelatively small difference in laser parameters (e.g. fluence) mayproduce a large difference in Ω. For the fluence outside the recommendedtreatment dosage (18 J/cm²), collagen denaturation is substantiallycomplete (100%), consistent with the expectation of clinical sideeffects. Thus, correlating the model calculations with the knownclinical tissue response to the Smoothbeam laser, it is found here thatnormal skin tissue can tolerate laser-induced thermal histories thatproduce Ω values greater than unity, specifically, values of at least1.2. Therefore, according to the present invention, 1.5 is identified asa reasonable approximate upper limit the value of Ω corresponding to theamount of collagen denaturation that is consistent with an advantageousclinical outcome and substantial avoidance of scarring. Ω=1.5corresponds to 78% collagen denaturation by the laser irradiation, or asubstantial amount of collagen denaturation but an amount that does notlead to clinically significant coagulative necrosis or scar formation.

Next, this finding of clinically acceptable Ω values for collagendenaturation is applied to a different laser wavelength, 1125 nm in thenear-infrared. In FIG. 3, the contour plot shows the effect ofirradiating skin with 10 W, at 1125 nm, for 28 s, with a 25° C. (roomtemperature) sapphire window in contact with the skin surface 4 before,during, and 28 s after the pulse, for a total treatment time δ of 1 min.The contour shown in FIG. 3 corresponds to the temperature within theskin at 1 min (that is, at the end of the total treatment time). Themodel assumes a 12 mm diameter circular irradiated spot on the skin,having flat-top energy distribution. Heating occurs throughout the fullthickness of the dermis. The horizontal gray line at 2.5 mm correspondsto the typical thickness of skin on the back, which is typically thethickest type of skin. The rationale for the choice of the 1125 nmwavelength, which is in the range of wavelengths previously identifiedas most preferred for soft tissue thermal therapy (K. McMillan et al.WO/2010/060097, US20100160904), is described in subsequent sectionsbelow. Table I shows the Ω values, as a function of depth in the skin,calculated using Eq. 1 and the Arrhenius parameters for collagendenaturation of skin, for the 10 W laser irradiation of FIG. 3. Themaximum Ω value is approximately 1.5, and is located between about 1.5mm and 2.0 mm deep in the skin, within the lower dermis.

To summarize the findings at this point, it has been determined thatskin tissue may be subjected to a thermal history that produces a damagevalue Ω of approximately 1.5, corresponding to percentage collagendenaturation of approximately 78%, without significant scarring or otheruntoward effects. This amount of thermal damage is significantly greaterthan the conventional Ω=1.0 or 63% damage for the threshold of thermalinjury. From this finding, new laser treatment parameters can bedetermined that produce maximum Ω values of approximately 1.5 at depthsthat extend deeply into the dermis for treatment of BCC.

To determine whether malignant cells residing within the collagen matrixof skin are effectively treated (eradicated) when subjected to thermalhistories that produce Ω of approximately 1.5 for collagen denaturation,the Arrhenius parameters for heat-induced killing of malignant cells areneeded. Arrhenius parameter data from a variety of sources are availablein the literature (see for example Feng Y, Oden J T, Rylander M N. JBiomed Eng 130; 041016, 2008, and He X, Bischof J C. Crit. Rev BiomedEng 31; 355-421, 2003). For three human tumor cell types, PC3, HeLa, andAT1, the parameters A and E are available from data corresponding to atemperature range of over 50° C. According to the present invention, itis necessary to use Arrhenius parameters derived from thermalexperiments that include temperatures over 50° C., as that rangecorresponds to the temperatures the skin reaches when irradiatedaccording to the present invention, for example as shown in FIG. 3.(Many studies in the literature present Arrhenius parameters for cellsor tissues determined from hyperthermia experiments within the range ofapproximately 40 to 50° C. range, which involves a different mechanismof thermal injury than that of the higher temperatures of the presentinvention. Hyperthermia involves heating to approximately 41 to 45° C.,whereas the term thermal therapy typically indicates heating within theapproximately 50 to 70° C. temperature range. Most Arrhenius data formalignant cells corresponds to the hyperthermia treatment range, ratherthan thermal therapy.)

TABLE I depth Ω (1 min) (z) collagen PC3 HeLa AT1 0.5 mm 0.006 0.2760.389 0.511 1.0 mm 0.360 6.048 1.090 13.584 1.5 mm 1.565 18.336 3.59043.925 2.0 mm 1.543 18.662 3.627 44.451 2.5 mm 0.715 10.900 2.010 24.9163.0 mm 0.213 4.598 0.783 9.883

Table I shows the Ω values for tumor cells subjected to the same thermalhistories as the skin in FIG. 3, as calculated herein using theappropriate Arrhenius parameters for thermal therapy. Accordingly, thesevalues correspond to the damage (death) that would be inflicted on tumorcells if they were contained within the dermis as the skin is heated bythe 10 W laser pulse. It is found that for each of the disparate threetumor cell types, the tumor cell damage is much greater than the damagein the form of collagen denaturation. (Ω=3 and 10 corresponds to 95% and99.995% lethal damage, respectively.) Tumor cell death is producedpreferentially at all depths, including at depths corresponding to thethickest skin (about 2.5 mm) This new finding leads to the conclusionherein that preferential or selective injury to malignant tumor cells,for example BCC tumor cells, can be achieved by heating skin usingthermal histories that substantially avoid coagulative necrosis orscarring characteristic of all prior art thermal laser treatments ofskin cancer. More specifically, an important new finding of the presentinvention is that tumor cells can be thermally injured to asubstantially complete extent, or killed so that the tumor iseradicated, by the application of thermal histories that substantiallyavoid scarring or other untoward cosmetic or functional outcomes of skintreatment.

Another aspect of the present invention is the choice of laserparameters. It is advantageous to treat skin cancer with a deeplypenetrating laser wavelength, specifically, a laser wavelength that iscapable of penetrating at least 3 mm, or the full thickness of thethickest skin tissue (approximately 2.5 mm) plus a portion of the uppersubcutaneous or adipose tissue. This objective is consistent with theclinical standard of excising the full thickness of skin, in surgicalexcision of skin cancer, although a significant advantage of the presentinvention is that it targets the tumor cells in the affected skin regionof a tumor, and substantially spares the normal skin. According to thepresent invention, a 3 mm depth of penetration is needed to treat, forexample, a mnBCC that comprises tumor cell nests that extend throughoutthe layers of skin on the back. Also according to the present invention,the power and irradiation time of the laser can be selected to providedifferent depths of maximum heating, according to the tumor type,anatomic location, and skin thickness. Although an advantageousembodiment of the present invention may use a laser as light source, itmay be appreciated that other light sources can also be used, forexample light emitting diodes, incandescent lamps, flashlamps or arclamps, and any other natural or artificial incoherent light source withor without optical filters to provide light of deeply penetratingwavelengths.

Another consideration is that BCC tumors may have variable amounts ofblood vessels within or at the periphery of the tumor. Use of awavelength that is strongly or preferentially absorbed by blood to heatthe tumor will lead to inconsistent results. Also, most skin tumors arelocated on the head or neck, and normal blood vessels in the vicinity ofthe tumor may be subject to iatrogenic damage if a wavelengthpreferentially absorbed by blood is used.

Therefore, according to the present invention, the wavelength used totreat the skin tumor should be deeply penetrating and not stronglyabsorbed by blood. These considerations were addressed in a previousinvention of the present inventor (US20100160904, WO/2010/060097A3) forthermal therapy of soft tissues. In that invention, the wavelength rangeof 700 nm to 1350 nm, more advantageously 1100 nm to 1350 nm, or yetmore advantageously 1100 nm to 1140 nm, was taught for thermal therapyof soft tissues including tonsils and solid tumors Skin is of coursesoft tissue and BCC and other NMSC are solid tumors. The sameconsiderations apply to the present invention.

In FIG. 4A, the 1/e depth of penetration z_(e) of light in human dermisis shown. z_(e) was calculated from the intrinsic optical properties ofhuman skin (μ_(a), μ_(s), and g), and the following equations:δ=1/√{square root over (3μ_(a)(μ_(a)+μ_(s)(1−g)))}  Eq. 2R _(d)=exp(−78μ_(a))  Eq. 3k=3+5.1R _(d)−2exp(−9.7R _(d))  Eq. 4z _(e)=δ(1−ln(k))  Eq. 5z_(e) is defined as the depth at which light intensity falls to 1/e ofthe intensity at the tissue surface. For human skin, the maximum depthof penetration z_(e) is about 5.6 mm at approximately 1091 nm, and z_(e)is at least 3.0 mm at wavelengths from 811 nm to 1310 nm. In FIG. 4A,the less advantageous wavelengths that correspond to z_(e) of less thanabout 3.0 mm are shaded.

It is recognized that there are different ways known in the art todefine and quantify the depth of penetration of light in the skin.Therefore, the advantageous wavelength range for treatment of skintumors may be described in an alternative, more general way aswavelengths over which the depth of penetration is at least a 0.54 (=3.0mm/5.6 mm) of its maximum value within the visible and near-infraredspectral region.

In FIG. 4B, the ratio of the absorption coefficient of dilute(hematocrit 5%) well-oxygenated blood to the absorption coefficient ofwater is plotted over the same spectral region. It is apparent that theratio is very high at wavelengths less than approximately 1100 nm, andthat at above approximately 1100 nm, the ratio drops rapidly to a valuethat is low and relatively constant. In FIG. 4B, the less advantageouswavelength region where blood absorption is high relative to water (themain component in soft tissue) is shaded.

FIG. 4C shows the spectral region that corresponds to both low bloodabsorption, and deep (approximately 3.0 mm or deeper) penetration oflight in skin tissue, as the unshaded region between 1100 m and 1310 nm.According to the present invention, this region, approximately 1100 nmto 1310 nm, is an advantageous region for thermal therapy of skin,including BCC thermal therapy. The 1100 nm to 1310 nm region is withinthe 1100 nm to 1350 nm region identified in the previous patentapplications (US20100160904, WO/2010/060097A2). Skin tissue (dermis) hasa scattering coefficient that is relatively high compared to many othersoft tissues (such as, for example, tonsil tissue), making it moredifficult for light to penetrate deeply. Therefore while any wavelengthin the previously identified 1110 nm to 1350 nm region may be usedadvantageously for thermal therapy of soft tissue including skin andskin cancer, the region 1100 nm to 1310 nm may be more advantageous forskin and skin cancer.

Also, according to the present invention, within the 1100 nm to 1310 nmrange of wavelengths, those corresponding to deepest penetration may beyet more advantageous. Therefore, wavelengths in the 1100 nm to 1140 nmregion may be highly advantageous. The wavelength of 1125 nm,corresponding to depth of penetration z_(e) of 4.6 mm, is an example ofa highly advantageous wavelength. FIG. 4D shows the 1100 to 1140 nmregion highlighted in light gray, and the 1125 nm wavelength in darkgray.

Light sources to implement the present invention are available.Considering first the advantageous wavelength region of approximately1100 nm to 1310 nm, choices of laser technologies that can producemultiwatt, continuous wave output include the ytterbium-doped fiberlaser, and the quantum dot semiconductor laser. Ytterbium fiber lasersproducing multi-kilowatt powers have been introduced for use inmaterials working and automobile manufacturing, and lower-power modelssuitable for the present application are commercially available. Forexample, IPG Photonics (Oxford, Mass.) produces a benchtop 20 Wair-cooled Yb fiber with a 3 meter delivery cable, center wavelength1120 nm, bandwidth 2 nm (fwhm), and visible aiming beam. The system canbe operated in CW mode or with externally controlled pump modulation.Because fiber lasers have a broad gain bandwidth there is thepossibility of developing a medical laser that operates over multiplewavelengths or is tunable, for example within the wavelengths of 1050 nmto 1120 nm in the case of Yb-doped fiber lasers, such that the lasercould be operated at 1120 nm for the present skin cancer application, orat 1064 nm for applications that the Nd:YAG laser is commonly used indermatology, plastic surgery, otolaryngology, and other medical fields.

Wavelengths shorter than 1100 nm, and longer than about 1280 nm can beobtained using GaAs and InP diode lasers, respectively, but untilrecently the intervening region was not readily available from a diodesource. In the past few years, however, efficient, high powersemiconductor lasers based on quantum dot (QD) nanotechnology have beendeveloped. QD lasers have advantages of enhanced gain for low operatingcurrent, high spectral purity (very narrow bandwidth), and minimaltemperature effects. Innolume, Inc. (Santa Clara, Calif. and Dortmund,Germany) has commercialized QD lasers based on InAs quantum dots in GaAswith AlGaAs barriers, all on GaAs substrates. Fiber coupled quantum dotlaser modules from this source producing 4 W at a center wavelength of1120 to 1130 nm with bandwidth 3 nm fwhm are available.

In addition to lasers, incoherent light sources may be used. One suchincoherent source is the tungsten halogen lamp. Because the halogen lamphas a broad emission in the visible and NIR, filters should be used toblock the emission of light outside the 700 nm to 1310 nm range, or morepreferably outside the 1100 nm to 1310 nm range. In addition,superluminescent diodes emitting in the 1100 nm to 1310 nm range havebeen demonstrated and may be used.

Although it is outside the advantageous wavelength range of 1100 nm to1310 nm, the neodymium YAG laser operating at 1064 nm has a long historyof medical use and may be used according to the invention. The 1064 nmYAG laser readily produces output powers in the range that would benecessary for it to be used as the light source in the currentinvention, and it is a reliable and relatively inexpensive laser wellsuited to fiber optic delivery. Similarly, high power diode lasers atNIR wavelengths of 810 nm, 940 nm, 980 nm and other wavelengths between700 nm and 1100 nm are readily available, of relatively low cost, andare familiar light sources for medical and surgical applications thatmay also be used according to the present invention. With wavelengthsshorter than about 1100 nm, additional care may be needed to avoiddamaging critical normal blood vessels in the vicinity of the irradiatedskin region, particularly when lesions on the face or neck are treated.Also, at these shorter wavelengths, results treatments may be lessconsistent due to variations in lesional vascularity.

FIG. 3 depicted full thickness heating of skin with 10 W radiation froma 1125 nm laser. By changing the laser power, irradiation time,irradiated spot size, and/or surface cooling parameters, the depth ofheating can be varied. For instance, FIG. 5 is a contour plot of skinirradiation with 1125 nm at 20 W, for 8 s, with contact cooling at 35°C. and no precooling, and a spot size of 12 mm. It can be seen, bycomparison with FIG. 3, that by increasing the laser power anddecreasing the irradiation time, that the region of maximum temperatureincrease is shifted closer to the skin surface. A laser source thatwould provide the parameters of either FIG. 3 or FIG. 5 is afiber-coupled quantum dot multichip laser diode module (LD-1120-MCP-20W,Innolume GmbH, Dortmund, Germany). Depending on temperature, the laseroperates with a center wavelength of between about 1120 nm and about1130 nm. The maximum current rating of 9.9 A for this laser modulecorresponds to an output of approximately 36 W.

The treatment of skin with a circular spot of 12 mm diameter withflat-top (homogeneous) energy distribution and surface cooling, modeledas in FIGS. 3 and 5, can be achieved with a handpiece that accepts theoutput of a the laser, transmitted through an optical fiber or othertransmission means known in the art.

According to the present invention, preferential damage to tumor cellscan be produced using a deeply penetrating laser wavelength atparameters that heat the tumor and surrounding normal skin, so that thetumor cells in all locations within the tissue are exposed to a thermalhistory that corresponds to a large damage integral Ω, for example a Ωof at least approximately 2, and more advantageously greater than 2, forthose cells, and, secondly, that that thermal history corresponds to adamage integral Ω for surrounding normal dermal collagen that is lessthan approximately 1.5. However, in the currently available clinicallaser treatments, the temperature within the tissue of the skintreatment site during irradiation is not measured and is unknown. Inorder to accurately determine Ω or any other measure of thermal injury,accurate temperature measurements are needed at representative pointswithin the volume of tissue where the skin tumor may be located, duringirradiation, and more advantageously before, during and afterirradiation, and more advantageously yet, before, during, and afterirradiation until the tissue has cooled. The present invention addressesthis need with a novel handpiece and method for measuring temperatureduring irradiation, at precise locations within the tissue that arefixed and defined relative to the skin surface and the position of theimpinging laser beam.

FIGS. 6A and B are side and end views, respectively, of one embodimentof a handpiece 1 for delivery of light from the light source to theskin, according to the invention. The handpiece 1 is coupled to the exitend of an optical fiber 2, such that light from the fiber is transmittedto an optical assembly 4 contained within a handpiece housing 3. Theoptical assembly may comprise one or more lenses to distribute the lightemitted from the fiber to a distribution that is advantageously appliedto the skin. For example, the optical assembly may comprise twoplano-convex lenses as shown in FIG. 6A to reimage the fiber exit faceonto the skin surface at some magnification and with an approximatelyflat-top or homogeneous light distribution at the image plane. The lightpassing through the optical assembly 4 is transmitted to a first window5 that is adjacent to a cooling fluid space 7 between the first window 5and a second window 6. Windows 5 and 6 are substantially transparent tothe laser light and may be made, for example, of glass, quartz, opticalplastic, or sapphire. Fluid may be passed through the space 7 fromcooling input line connector 8 a to cooling output line connector 8 b.Connectors 8 a and 8 b are in turn attached to cooling lines 12 a and 12b, respectively. It may be understood that the handpiece, as describedabove, can be modified to produce an irradiated spot of differentdiameters or dimensions, or different shapes (square, rectangular,oblong, hexagonal, for example) by those skilled in the art.

Attached to the handpiece is a grid element 9 that is made of a laserresistant material that is transparent or semi-transparent to the laserwavelength, and which comprises at least one temperature sensor needle10 connected with at least one lead wire 11. The grid element 9 has aproximal surface 9 a that is in contact with or adjacent to the distalsurface 6 a of the second window 6. When the handpiece 1 is brought intocontact with the skin, the grid element distal surface 9 b is in contactwith the skin, and the sensor needles 10 are inserted into the skin suchthat the temperature sensors are at located at points within the skinwhen the laser is activated and light is applied to the skin. Inadvantageous embodiments, the grid element 9 with sensor needles 10 is adisposable component of the laser handpiece 1. The grid element 9 mayhave an edge section 9 e with an edge section inner surface 9 f that isin contact with the handpiece 1 or the window 6 when the grid element 9is attached to the handpiece 1.

The end view of FIG. 6B shows open areas 9 d in the grid element 9. Theopen areas allow light to pass unimpeded from the window 6 to the skin,when the handpiece is in contact with the skin. In more advantageousembodiments, the total area of the open areas 9 d is a substantialfraction of the distal surface area of the window 6. The open areas 9 dcan have any shape, number, size, or relative placement within the gridelement 9. The proximal ends of the sensor needles 10 are embedded in orattached to the grid element 9, and the sensor leads 11 travel throughchannels 9 c in the grid element, before exiting the grid element. Thechannels 9 c may be reflectively coated or otherwise shielded to preventlight-induced damage to the sensor leads 11. Alternatively, the sensorleads 11 may themselves be coated or shielded.

Grid elements with sensor needles were described in a previous inventionof the present inventor (US20100160904, WO/2010/060097A3) formeasurement of temperature during thermal therapy of tonsils and othersoft tissues.

Although the handpiece is designed so that the fluid in space 7 will notbe in contact with tissue, the light-transmitting fluid should benontoxic as well as having good heat transfer properties. Fluids thatare appropriate include Fluorinert™ (3M, St. Paul, Minn.), specifically,FC-77 or other Fluorinert™ fluids that have low vapor pressure at roomtemperature. Water and aqueous solutions may also be appropriate fluids.The fluid may also be a nontoxic gas, for example nitrogen or air.

In alternative embodiments, the windows 5 and 6 may be omitted, and thegrid 9 attached directly to the housing 3 of the handpiece 1. In suchembodiments, the skin surface may be precooled, for example with an icepack or cold air. Or, the skin surface may be cooled during irradiationby flowing cold fluid such as cold air or cold nitrogen, directly on tothe skin and grid element 9 using a separate cold air machine (forexample, Zimmer Cryo 6, MedizinSystems Inc, Irvine Calif.). Various suchcooling elements may be used according to the invention, including butnot limited to the cooling layer 7 of the handpiece 1, a source of coldgas, a cooling gel, or a cold pack.

In some advantageous alternative embodiments, the cooling layer 7 andwindow 6 may be eliminated, and the skin passively cooled by contactwith window 5 during irradiation. Window 5 may be precooled, before thehandpiece is brought into contact with the skin, or after contact butbefore irradiation begins.

In other advantageous embodiments, the embodiment shown in FIGS. 6A and6B for example may be used with window 6 at room temperature or atemperature that is close to normal physiologic temperature (37° C.) orany temperature in between. In more advantageous embodiments, after theend of laser irradiation the window 6 is rapidly cooled to a temperaturewell below room temperature to quench the laser-induced heat and stopthe process of thermal damage. The quenching temperature should not beso cold as to substantially freeze the skin or cause freezing injury tothe skin. For example, the handpiece of FIGS. 6A and 6B may be used toirradiate the skin surface with no fluid flowing through space 7 duringthe laser pulse, but at the end of the laser exposure a flow of cold airor cold liquid may be passed through said space.

It may be appreciated that the handpiece 1 may be of many differentconfigurations known in the art. For example, instead of deliveringlight from a light source to the handpiece by means of an optical fiberor other transmission device, the light source may be in the handpiece.For instance, the handpiece may contain multiple diode lasers positionedso that their combined output irradiates the skin surface when thehandpiece is held in contact with the skin. Or, the handpiece maycontain a tungsten halogen lamp inside a reflective chamber, such thatthe lamp light is directed to the skin surface when the handpiece isheld in contact with the skin.

Likewise, the irradiated spot on the skin produced by the handpiece maybe any shape (circular, oblong, square, rectangular, hexagonal,polygonal, or of nongeometric shape), and any diameter, size, ordimension that is advantageous for treating lesions of different sizeson different sites of the body.

In advantageous configurations of the invention, the apparatus of theinvention may have interchangeable or adjustable handpieces with morethan one size or shape of irradiated spot, for convenient treatment ofdifferent anatomic locations. Also, a large lesion can be treated bymoving the handpiece from spot to spot with or without overlap, to coverthe entire lesion.

According to the present invention, the temperature at one or morepoints within the skin region being treated can be monitored using thetemperature sensors of the grid element 9, so that the damage integral Ωcan be calculated during the treatment for both normal dermis and tumorcells, using Eq. 1. In this way, the operator can ensure that, first, iftumor cells are present at the locations of the one or more temperaturesensors, those tumor cells have been exposed to a thermal history thatcorresponds to a large damage integral Ω, for example a Ω of at leastapproximately 2, and more advantageously greater than 2, for tumorcells, and, secondly, that if collagen fibers of normal dermis arepresent at said locations of the one or more temperature sensors, thosecollagen fibers have been exposed to a thermal history that correspondsto a damage integral Ω for normal dermal collagen that is less thanapproximately 1.5. In some embodiments of the invention, a display panelallows the operator to monitor temperature at each of the sensors, andalso to continuously monitor Ω for tumor cells and Ω for dermalcollagen, as the treatment progresses and thermal damage accumulates, atthe location of each of said sensors. In advantageous embodiments of theinvention, there is more than one temperature sensor. In otheradvantageous embodiments of the invention, the more than one temperaturesensors are located at different depths within the skin tissue, forexample at a depth corresponding to epidermis, a depth corresponding todermis, and a depth corresponding to subcutaneous (adipose) tissue. Inother advantageous embodiments of the invention, the more than onetemperature sensors are located at different distance from the center ofthe impinging laser beam, within the skin tissue. In advantageousembodiments of the invention, the more than one temperature sensors arelocated at different depths corresponding to the location of tumor cellswithin the skin. In another embodiment of the invention, the signalsfrom the temperature sensors are use to increase or decrease laserpower, to in turn increase or decrease the rate of damage accumulationdΩ/dt in the skin, for either tumor cells or dermis, for better controlof treatment outcomes.

For treatment of lesions with tumor cells extending into thesubcutaneous tissue, the damage integral Ω for adipose tissue may alsobe calculated from temperature measurements in that location.

The grid element 9 may have open areas 9 d of any size, number, andshape. In FIGS. 7A-B, another embodiment of the grid element is shown.FIG. 7A shows the grid element so that the distal surface 9 b is facingupwards. FIG. 7B shows the grid element so that the proximal surface 9 ais facing upwards. The grid element 9 may attach to the window 6 of thehandpiece or to a surface of the handpiece itself by snap fitting,pressure fitting, set screw, or any other means known to those skilledin the art. In some embodiments, a thin, substantially transparentbiocompatible polymeric sheet can be placed adjacent to the handpiecewindow prior to attachment of the grid element, to protect the windowfrom biological contamination during treatment of a lesion. Thepolymeric sheet may be polyimide, polyurethane, or any such materialknown in the art, and may be disposable.

When grid element 9 is a disposable component, the tissue penetratingsensor needles 10 do not require sterilization after use. The remainingcomponents of the handpiece can be cleaned as necessary and reused. Itis advantageous to separate the handpiece with its optical assembly fromthe affixed sensor needles or other components for which reuse inpatients is impractical. Optical components are expensive and mayrequire precise relative alignment. According to the present invention,optical components can be kept substantially intact and reused, whilethe grid elements with needles that are inserted in the tissue can bedisposed of after use so that the procedure is convenient, practical,and economically advantageous.

In one embodiment, the grid element is made of a plastic material thatsubstantially transmits light of the wavelength or wavelengths emittedby the light source of the apparatus. In a specific embodiment, the gridelement is made of polyetherimide resin, e.g. Ultem® (SABIC InnovativePlastics). In another specific embodiment, the grid element is made of apolycarbonate resin, e.g. Makrolon® (Bayer MaterialScience). The portionof the skin surface touching the distal surface 6 a of the window 6within the open areas 9 d of the grid can be directly cooled by windowdistal surface 6 a, and the portion of skin surface touching a portionof the grid element distal surface 9 b can be cooled by contact with thegrid element which in turn is in contact with the window 6 and/or byheat transfer from adjacent skin tissue directly cooled by the contactsurface. Thus, a key aspect of the invention is that the grid element ofthe invention provides for the insertion of one or more temperaturesensors at predefined distances in the tissue from thelight-transmitting contact distal surface 6 a of the window 6, by ameans that does not interfere substantially with either delivery oflight to the tissue or to the effective cooling of the tissue. In FIGS.6A and 7A-B the attached needles are depicted as extending in adirection perpendicular to the window distal surface 6 a. The needlesmay also be attached with an angle relative to the surface 6 a.

In advantageous embodiments of the invention, each handpiece 1 of theinvention is supplied with multiple grid elements 9, said grid elementshaving different numbers, lengths, density, or arrangement of needlesensors appropriate for certain lesion types or anatomic locations. Forexample, for treatment of a BCC on the back, where skin is thick, or fortreatment of a lesion suspected of being deep at any anatomic location,a grid element with at least one needle of length approximately 2.5 mmor longer is used. For tumors located on thinner skin and/or overlyingbone or cartilage, the longest needle on a grid element may besubstantially shorter than 2.5 mm. For handpieces with larger irradiatedspot sizes, multiple needles positioned near the center of the beam, atthe edge of the beam, and at intervening positions may be used. Forhandpieces with small irradiated spot sizes, for example handpiecesuseful in treating small tumors in difficult anatomic locations such asnear an eyelid, a single short sensor needle may be used.

A temperature sensor that is suitable for use in a sensor needleaccording to the present invention includes a thermocouple or athermistor. Thermocouples housed in small diameter hypodermic needlesare commercially available. Type T thermocouples are available instainless steel hypodermic needle probes as small as 200 micron diameterfrom a commercial source (HYPO Mini-Hypodermic probe, OmegaEngineering). Other examples of a temperature sensor in a stainlesssteel needle is the MLT1406 Needle Microbe Thermocouple (ADInstruments),and the MT-23 635 micron diameter needle probe (Physitemp Instruments,Clifton, N.J.). The time constant of such needle probes is on the orderof 0.1 s, making them suitable for temperature monitoring and control.In the present invention, sensor needles are of a diameter about 200microns to about 700 microns. In one embodiment, the sensor needlediameter is about 200 microns to about 500 microns. In one embodiment ofpresent invention, the sensor needles are made of medical gradestainless steel (316, 316L or vacuum melted type 316L). In anotherembodiment, the sensor needles are made of medical grade titanium(unalloyed commercially pure CP grades 1-4) or titanium alloys(including Ti-6Al-4V ELI, Ti-6Al-4V, Ti-6Al-7Nb, Ti-3Al-2.5V,Ti-13Nb-13Zr, Ti-12Mo-6Zr-2Fe, Ti-15Mo) Other metallic materials thatcan be used to make the sensor needles include silver, platinum,tantalum, niobium, zirconium and zirconium alloys, shape memory alloysbased on the nickel-titanium binary system, tungsten and tungstenbronzes, and cobalt alloys (Elgiloy and MP35N). Needle probes made ofmany metallic materials, including stainless steel, will absorb lightincluding near infrared light of the range of about 1100 nm to 1350 nmto be directly heated. Therefore, in one embodiment, the needle is madeof a metal that substantially reflects light, and in another embodiment,made of gold, which is highly reflective of light. In anotherembodiment, a coating that substantially reflects light is applied tothe exterior surface or exterior and interior surface of a sensorneedle. For example, a gold coating is applied to the surface of thesensor needle. Use of a gold needle or a gold-coated needle will reducemeasurement artifacts due to direct absorption of light by the sensorneedle, and will allow the tissue temperature to be measuredsimultaneously with tissue irradiation, for the most precise and rapidcontrol of the irradiation process. In the absence of a reflectivecoating, the irradiation process can be intermittently halted to measuretemperature after the needle probe equilibrates with the surroundingtissue. Briefly halting the irradiation will allow accurate temperaturemeasurements to be made with, for example, a standard stainless steelneedle probe, although the total treatment time will be slightly longeras a result. Alternatively, according to the present invention, accuratetemperature measurements may be made with a probe made of stainlesssteel or other material that absorbs light, if the signal is processedto separate out the exponential artifact signal according to methodsknown to those skilled in the art.

Thermocouple needle sensors are advantageous because they areinexpensive, rugged, reliable, and simple to use. Other means oftemperature sensing include noninvasive, noncontact temperature sensingof the skin, such as by collecting and analyzing radiation emitted bythe skin FIG. 8 is a schematic depiction of a simple embodiment of anapparatus (100) of the invention. A handpiece 1 with attached gridelement 9 is connected to a system comprising a controller unit 110, acooling unit 130, and a laser unit 120, via needle sensor leads 11,coolant lines 12 a and 12 b, and optical fiber 2, respectively. Thecontroller unit will contain a microprocessor for processing the sensorsignals and calculating temperature and Ω, and may have a display 110 afor visualization of the temperature or damage SZ at the locations ofthe sensors in the skin. The controller may also have a display panel110 b for adjusting the laser parameters or operating the apparatus,including the cooling system. The laser unit will have a light outputaperture 120 a to which the optical fiber connects. The laser unit maybe more generally a light unit, when incoherent light sources are used.The cooling unit may be a recirculating chiller or a cold air machine,for example.

There is considerable flexibility to cooling in the present invention.When used, cooling can be initiated before the handpiece is placed onthe skin, before irradiation begins or during irradiation, or afterirradiation ceases. Initiation and ending of cooling and irradiation mayall be performed under operator control with operator monitoring of thetreatment progress, or may be under microprocessor control. Coolingtemperature may be varied during the time the handpiece is on the skin.

A simple treatment schema for skin cancer thermal therapy is shown inFIG. 9.

In advantageous embodiments of the invention, the epidermis is protectedfrom the heat generated by high radiant fluence rates caused bybackscattering of light within the tissue by surface cooling. This hasthe advantage of protecting normal epidermis in the vicinity of a skintumor and minimizing scarring. However, skin tumor cells may be within,closely adherent to, or adjacent to the epidermis overlying a skintumor. In that case, surface cooling and epidermal protection may reducethe thermal damage of the superficial tumor cells. Therefore, in anadvantageous embodiment of the invention, thermal therapy is combinedwith topical administration of a antineoplastic or anticancer agent toincrease tumor cell killing throughout the tumor, and especially at ornear the epidermal surface. This may be accomplished by application ofthe topical drug after laser treatment. However, because topical drugexposure is highly dependent on the epidermal permeability, andepidermal permeability in the region of a BCC or other lesion may be lowor high depending on how intact the stratum corneum is, topicalanticancer or chemotherapeutic drugs as used in the prior art fortreatment of skin cancer have inconsistent and inadequate efficacy. Amore consistent drug exposure is advantageous. The present inventionaddresses this problem by the use of a grid element that increasesepidermal permeability in a consistent manner.

FIG. 10 shows a grid element 9 with an array of permeability needles 9 gextending from the grid distal surface 9 b. The grid element also hassensor needles 10 for measuring tissue temperature. The permeabilityneedles 9 g produce holes through part or all of the epidermis, so thatthe topical drug circumvents the primary barrier to the skin. Inadvantageous embodiments, the permeability needles are arranged in adistribution that includes most of the irradiated area on the skin. Thepermeability needles may be hollow or solid, and may be made of anyrigid, biocompatible material that is strong enough to pierce the skin,including the materials listed above for the sensor needles.

The permeability needles may be of the same or similar diameter or gaugeas the sensor needles described previously, or may be much smaller, forexample microneedles.

The permeability needles 9 g can be made from or coated with a material,such as gold, that is reflective of near infrared light. However, inadvantageous embodiments of the invention, the permeability needles areuncoated or partially coated, so that they absorb radiation and areheated during the skin irradiation. In this manner, the tissuesurrounding the holes created by the needles may be at least partiallycoagulated or denatured, and the holes will retain their patency for alonger time.

In embodiments of the invention using multiple temperature sensorneedles, or in treatment of skin tumors that have a defective or damagedepidermis, permeability needles may be unnecessary to achieve adequateand consistent drug penetration through the epidermis.

A simple treatment schema for skin cancer thermal therapy that includestopical administration of an anticancer drug is shown in FIG. 11. Thegrid element of embodiments of the invention used in this schema mayhave permeability needles and sensor needles, or only sensor needles,

An important aspect of be present invention is that it may be used withany topical or surface-applied drug or therapeutic agent, for animproved treatment of skin cancers and other lesions of the skin.Creation of holes in the stratum corneum and the epidermis will increasepermeability of the epidermis to any drug or agent, regardless of thedrug's chemical properties, for example its lipophilic or hydrophilicnature, molecular size, molecular charge, or its formulation (solution,carrier, emulsion, cream, and the like). Drugs may includechemotherapeutic agents, cytotoxic drugs, bioreductive drugs,antiproliferative agents, retinoids, vitamins, antioxidents,anti-angiogenic agents, immunomodulatory agents, photodynamic drugs,pro-apoptotic drugs, antimetabolites, COX inhibitors or any other agentsthat may be useful directly or indirectly in killing or damaging, orreducing the growth or proliferation of, tumor cells, malignant cells,dysplastic cells, diseased cells or abnormal cells.

A specific example includes vitamin D and its analogs, which recentresearch has shown to have immunomodulatory, antiproliferative, andprodifferentiative effects. This group of drugs includes calcipotriol(calcipotriene), a synthetic vitamin D₃ analog used for the treatment ofpsoriasis, and available in a 0.005% ointment or cream formulation(Dovonex, Warner Chilcott, Rockaway N.J.; Psorcutan, Intendis, Germany).Repeated application of topical calcipotriol over a period of severalweeks has recently been reported in the medical literature to have someefficacy in treatment of actinic keratoses (AK), a premalignant or earlyform of squamous cell cancer (SCC) of the skin, in treatment of warts,benign viral tumors of the skin, and in treatment of Kaposi's sarcomaand cutaneous T-cell lymphoma. The naturally occurring active form ofvitamin D₃, calcitriol (Vectical, Galderma, 3 mcg/g topical) hasrecently been approved in the US for treatment of psoriasis. Bothcalcipotriol and calcitriol have poor penetration through intact stratumcorneum. When used according to the present invention, and applied tothe site of a skin lesion after the skin tissue has been made morepermeable, proliferative cells such as BCC cells may have much greaterexposure to vitamin D analogs including calcitriol and calcipotriol, fora highly effective treatment.

Topical application of the retinoid tazarotene (0.1%) on a daily basisfor up to 8 months has been reported to provide complete or partialresults in treatment of BCC. Tazarotene (Tazorac, 0.05% or 0.1% gel,Allergan, Irvine Calif.) is approved as a topical treatment forpsoriasis and acne; however retinoid drugs are also known to control thedevelopment and spread of cancer cells and cell proliferation.Tazarotene has limited skin penetration, due to the stratum corneumbarrier, which may account for the lengthy treatment regime andincomplete efficacy for BCC treatment. All-trans-retinoic acid has shownantiangiogenic and anticancer properties when given intravenously. Withthe present invention, it is possible to apply all-trans-retinoic acidtopically as a treatment for skin cancer.

Another example of a cytotoxic drug that may be used according to thepresent invention is a 6% solution of miltefosine (Miltex, Asta Medica,Germany). Miltefosine acts on cell membrane phospholipids and has beenused with some reported efficacy in treatment of skin metastases inbreast cancer and cutaneous T cell lymphoma, with daily application forat least several weeks. Miltefosine efficacy for those skin tumors aswell as BCC will increase with the present invention. Yet another groupof therapeutic agents that may be used advantageously according to thepresent invention are COX inhibitors. Examples include diclofen, anonsteroidal anti-inflammatory drug and nonspecific COX inhibitor thatis used in a 3% gel formulation (Solaraze, PharmaDerm, Melville N.Y.)for treatment of AK; celecoxib, valdecoxib, and sulindac, among others.

Antioxidants have been shown to have promise in treatment and preventionof cancer. Topical treatment with resveratrol, an antioxidant found ingrapes and berries, black raspberry extract, pomegranate seed oil, grapeseed proanthrocyanidins, beta carotene, ascorbic acid, and lycopene areexamples.

The above is only a partial listing of drugs or therapeutic agents thatare useful according to the present invention. Also, of those described,alternative formulations or dosages may prove advantageous in treatmentof tissue modified by the laser treatment of the invention. Furthermore,combinations of two or more drugs may be used with said laser treatment.

An important aspect of embodiments of the invention is that exposure toa topical drug or anticancer agent by cells that are thermally injuredwill increase injury to those cells. For example, cells that are injuredby heat from the thermal laser will receive further injury from thecytotoxin or anticancer agent. In advantageous embodiments, sublethalthermal damage will be augmented by the drug exposure to produceirreversible cell death in the tumor. In these embodiments of theinvention, for given thermal history Ω for tumor cells is increased,compared to thermal laser exposure alone, whereas Ω for collagen fibersis unchanged Appropriate values of A and E in the Arrhenius equation canbe experimentally determined at in tissue or cells in the presence ofdrug, to allow the calculation of Ω for exposure to temperatures in therange of 50° C. and higher for before, during, and after skinirradiation. A and E for cells and tissue can be determined fromisothermal temperature exposures, according to methods known in the art.A key important aspect of these embodiments is that the physical processof collagen denaturation by heat will be substantially unaffected by thepresence of cytotoxic drugs, whereas tumor cells will receive asignificantly increased insult, further increasing the differencebetween dermal collagen damage and tumor cell damage for a given thermalhistory during treatment. In these embodiments of the invention,efficacy in eradication of malignant cells is further increased whilepreserving normal skin tissue.

In another embodiment of the present invention, the thermal laser orlight treatment in the approximately 1100 nm to 1310 nm range may becombined with a vascular laser treatment intended to selectively damagetumor cells. The use of a vascular laser for treatment of tumors of theskin and other epithelial tissue layers has been described by thepresent inventor in WO/2010/102099A1 Method and Apparatus for CancerTherapy. Vascular targeting selectively damages blood vessels, andinduces hypoxia in the tumor cells that rely upon that vasculature. Bythis mechanism, vascular targeting may induce tumor cell death. Theindirect induction of tumor cell death by hypoxia can be combined withthe direct induction of tumor cell death by heating with a thermallaser.

For example, in one embodiment, a thermal laser treatment using a laseror light source in the approximately 1100 nm to 1310 nm range asdescribed above is followed by a treatment with a vascular laser orlight source, for example a pulsed dye laser, KTP laser, frequencydoubled Nd:YAG laser, alexandrite laser, or filtered flashlamp (intensepulsed light source). These vascular targeting devices are well known inthe art, are routinely used for treatment of cutaneous vascular lesionssuch port wine stain birthmarks and telangiectasias, and typicallydeliver light to the skin using a handpiece held adjacent to or incontact with the skin, and also typically employ surface cooling.

FIGS. 12 and 13 depict the results of Monte Carlo simulations of theeffect of an exemplary vascular laser on skin. The calculation volume isrectangular with 2 cm by 2 cm surface area and a depth of 1 cm. Theresolution of the Monte Carlo calculation in each direction is 50 μm.One million photons are included in each calculation, which assumes aflat-top laser beam incident on the skin tissue surface. Heat transfercalculations are done numerically by a finite-difference method.

In these model calculations, tissue is represented by the followinglayers, beginning with the topmost or most superficial layer: (1)epidermis, assumed to be a layer 100 μm in thickness, (2) dermis, 2.6 mmin thickness, and (3) subcutaneous tissue, with infinite thickness. Alsoin the model, the microvasculature of the dermis is represented by twohorizontal 50 μm diameter blood vessels located 0.5 and 2.5 mm under thesurface, representing the upper and lower vascular plexuses,respectively, and a series of vertical 50 μm diameter blood vesselsspaced 1 mm apart, connecting the two horizontal vessels. The verticalvessels represent the ascending and descending vessels of the dermis.Not explicitly include are capillary sized vessels, which are less than10 microns in diameter and too small to be modeled, however theabsorption coefficient for dermis used in the model reflects the bloodcomponent of capillaries. Also not explicitly included in the model isthe stratum corneum of the epidermis, which is only about 20 μm thick.

In FIG. 12, the results are shown, in the form of a contour plot oftemperature at the end of the laser pulse, as a function of locationunder the skin surface. In this and the other contour plots providedherein, y is a dimension parallel to the tissue surface, z is the depthperpendicular to the surface, and the origin of the coordinate system isthe center of the laser beam on the tissue. In this particularcalculation, the model assumes pulses with 0.5 ms pulse duration andfluence (energy density on the skin surface) of 4 J/cm². The pulse has adiameter on the skin surface of 7 mm, and a top-hat, evenly distributedbeam profile. (The choice of laser pulse diameter was limited by theresolution and calculation volume in the mathematical model, and doesnot represent a limit in implementation.) The skin is exposed to roomtemperature air during the non-contact pulse. As is known to thoseskilled in the art, these laser parameters from a 585 nm PDL typicallyproduce microvascular injury within the dermis, evidenced by purpura orbruising. As can be seen in FIG. 12, the model calculation accuratelypredicts vascular coagulation across the horizontal vessel of the upperplexus, as well as upper portions of the vertical vessels, in agreementwith clinically observed purpura. The 4 J/cm² laser pulse producestemperatures of at least 70° C. in the vertical blood vessels down to adepth of 1.5 mm near the center of the beam, and 1.0 mm near the edges.In agreement with clinical observation, the PDL at this fluencesubstantially avoids temperatures corresponding to thermal injury to theoverlying epidermis.

In FIG. 13, the same model is used with pulses of higher fluence (9J/cm2). This fluence is seen to produce increased heating of the dermalmicrovasculature, with blood vessel coagulation expected down to about1.5 mm at the edges and 1.9 mm near the center. Again, the areas ofdermis surrounding the blood vessel are substantially unheated. Theepidermis shows heating in the 60 to 70° C. range, which may be expectedto cause some thermal injury within this layer. Again, this calculationis in agreement with clinical experience, and supports the accuracy ofthe mathematical model developed herein. Clinically, in the treatment ofskin lesions such as PWS birthmarks, these laser parameters wouldrequire skin cooling to protect and preserve the epidermis for optimalcosmetic outcome. Skin cooling may take the form of a cryogen spray, achilled contact element such as a window or lens, a cooling fluid, coldair applied to the skin surface before, during, and/or after a laserpulse, or any other means known in the art.

By combining the thermal therapy with vascular targeting, efficacy maybe increased without substantial loss of preferential tumor cellkilling. The important aspect of combining vascular laser treatment andthermal laser treatment of skin tumors is that both treatments areselective and sparing of normal tissue. The vascular treatmentselectively injures dermal microvasculature that supply tumor cells,inducing hypoxia and indirectly killing those cells. The thermal lasertreatment preferentially kills tumor cells, directly, by heating thosecells. The spatial range of the two therapies overlaps, but the vasculartreatment has its greatest effect in the superficial and mid dermis,whereas the thermal laser treatment is capable of having a strong effectdown to the deep dermis or below. The mechanism of action of thevascular and thermal treatments are different, allowing the two to becombined to eradicate tumor cells throughout the entire tumor fromepidermis to subcutaneous tissue, and still maintain selectivity fortumor cells

The present invention can be implemented by combining the thermaltherapy pulse and the vascular treatment pulse in either order. It isrecognized herein that is that when thermal laser therapy follows theproduction of purpura by a vascular targeting treatment, the purpura isindicative of altered optical properties of the skin. Specifically,purpura is a discoloration that is indicative of thermally denaturedblood. It is known that blood in vessels heated by lasers or light mayundergo oxidation to a hemoglobin species referred to a methemoglobin,and that methemoglobin absorbs more strongly than oxyhemoglobin atlonger wavelengths in the near infrared. According to the presentinvention, it is advantageous to avoid strong absorption of laser lightby the denatured blood containing methemoglobin, in a region of the skinthat has been previously treated with a vascular laser to producepurpura.

FIG. 14 shows the absorption spectra of the three hemoglobin speciesoxyhemoglobin, deoxyhemoglobin, and methemoglobin. It is apparent thatmethemoglobin absorbs much more strongly in the 1125 nm to 1310 nmregion than does oxyhemoglobin, the predominant species in welloxygenated blood. However, well oxygenated blood undergoes two changeswhen it denatures—oxidation to methemoglobin, and loss of oxygen. Thusthere is also an increase in deoxyhemoglobin. Representativeconcentrations in denatured blood of a purpuric skin area are 20%oxyhemoglobin, 30% methemoglobin, and 50% deoxyhemoglobin. The spectrumof this representative purpuric blood was calculated and is also shownin FIG. 14. It is found that the conversion to deoxyhemoglobin offsetsmost of the change to methemoglobin the 1125 nm to 1310 nm region, sothat the increase in absorption of the hemoglobins in the denaturedblood is only slightly higher than that of oxyhemoglobin. This novelfinding allows wavelengths of approximately 1125 nm to 1310 nm to beused to treat skin tumors in skin that has first been treated with avascular laser or other light source that has thermally injured dermalblood vessels so as to produce purpura. In addition to 1125 nm, anotheradvantageous wavelength for thermal therapy following vascular treatmentis shown in FIG. 15. At approximately 1270 nm, the depth of penetrationof light is approximately 3.6 mm, and interference from denatured bloodis low.

A simple treatment schema according to the present invention combiningthermal therapy with vascular targeting is shown in FIG. 16. It may beparticularly advantageous to further cool the skin after thermal therapybut before vascular targeting, so that the skin is at physiologictemperature and responds to vascular targeting in a consistent,predictable manner.

Another treatment schema is shown in FIG. 17, for treatment according tothe invention with thermal therapy, vascular targeting, and a topicalanesthetic agent. In this schema, vascular laser irradiation of a skintumor is followed by application of topical anesthetic to the tumor siteon the skin. In some advantageous embodiments, an ablation elementattached to the vascular laser handpiece produces an array of ablationsin at least the stratum corneum of the epidermis of the skin tumor siteduring vascular laser irradiation, said ablations increasing thepermeability of the epidermis. The topical anesthetic agent is appliedimmediately after irradiation when the vascular handpiece is removedfrom the skin surface, or, in some embodiments, after the formation ofpurpura at the irradiation site. In purpuric skin, dermal permeabilityis reduced because the reduction in blood flow reduces uptake of drug bymicrovasculature. Consequently, the drug stays in the dermis longer,dermal drug exposure is increased, and the potentially deleterioussystemic uptake of the topical anesthetic drug is reduced. The thermallaser irradiation is applied after the anesthetic drug has been on thepurpuric skin for a sufficient time to produce numbing of the treatmentsite and after the topical drug is removed from the skin. Thermal laserirradiation is applied with monitoring of temperature and damage Ω, andin advantageous embodiments includes skin cooling. In embodiments of theinvention depicted in the schema of FIG. 17, effective tumor treatmentis achieved with a concomitant reduction in pain from the thermal laserirradiation.

The effect of the combination of treatments (thermal and vascular) isrepresented schematically in FIG. 18. An upper region, marked in thefigure with a dashed line, is subjected to vascular coagulation by thevascular treatment, and a low region, marked with a solid line, isheated by the thermal laser. A region of overlap, marked with diagonallines, is significantly affected by both modalities. It will beappreciated that the actual extent of each of the two treatments will bedependent on choice of wavelength, fluence, pulse duration, cooling, aswell as the characteristics of the lesion and the skin where it islocated. An important aspect of the combination of the two treatmentmodalities is that the treatments may be temporally separated, withintervening skin cooling in some embodiments, so that nonselectiveheating by the vascular laser is substantially prevented in the regionof overlap. The mechanism of action of the vascular and thermaltreatments are different, allowing the two to be combined in eitherorder to selectively eradicate tumor cells throughout the entire tumorfrom epidermis to subcutaneous tissue. Yet another aspect of theinvention is that topical anticancer or chemotherapeutic agents appliedto the tissue will (1) be retained longer and penetrate deeper in dermistreated by vascular targeting, (2) further increase the amount of tumorcell death in tumor cells that have been subjected to vascularlaser-induced hypoxia and thermal laser-induced heating.

Another treatment schema is shown in FIG. 19, for treatment according tothe invention with thermal therapy, vascular targeting, and a topicalanticancer. In this schema, vascular laser irradiation of a skin tumoris followed by application of topical anticancer drug to the tumor siteon the skin. In some advantageous embodiments, an ablation element 30attached to the vascular laser handpiece 1 produces an array ofablations in at least the stratum corneum of the epidermis of the skintumor site during vascular laser irradiation, said ablations increasingthe permeability of the epidermis. The topical drug is appliedimmediately after irradiation when the vascular handpiece is removedfrom the skin surface, or, in advantageous embodiments, after theformation of purpura at the irradiation site. In purpuric skin, dermalpermeability is reduced due to a reduction in blood uptake of anticancerdrug, to increase dermal drug exposure and reduce possibly deleterioussystemic uptake of the drug. The thermal laser irradiation is appliedafter the anticancer drug has been on the skin for a sufficient time toachieve therapeutic levels of exposure to at least a portion of thedermis to said drug, at which time the topical drug is removed from theskin. Drug application times may be on the order of minutes to hours, orovernight. Before thermal laser irradiation, the drug is removed fromthe skin. Thermal laser irradiation is applied with monitoring oftemperature and damage Ω, and in advantageous embodiments includes skincooling. Use of permeability needles may be omitted with in theembodiment the anticancer drug is applied to the skin prior to thermallaser irradiation. Temperature at the location of each sensor needle ismonitored to ensure that the tumor cells have been exposed to a thermalhistory that corresponds to a large damage integral Ω, for example a Ωof at least approximately 2, and more advantageously greater than 2, fortumor cells, and, secondly, that the damage integral Ω for normal dermalcollagen that is less than approximately 1.5 at the location of eachsensor needle. In embodiments of the invention depicted in the schema ofFIG. 19, highly effective and selective tumor treatment is achieved witha combination of indirect tumor cell killing by hypoxia induced byvascular targeting, direct thermal injury to tumor cells by thermallaser irradiation, and direct tumor cell killing by the cytotoxic oranticancer drug.

In some embodiments of the present invention, the vascular lasertreatment will include an ablation element attached to the distal end ofthe vascular targeting handpiece to increase the permeability of theepidermis of the skin. Ablation elements were described inWO/2010/102099A1 Method and Apparatus for Cancer Therapy. The concept ofthe ablation element is shown in the embodiment of FIG. 20. The ablationelement 30 consists of a substantially transparent substrate 31, with anarray of embedded chromophore material elements 32, with a substantiallytransparent contact window 33 covering said chromophore materialelements. The ablation element transmits a substantial portion of thelight from the vascular targeting laser to the skin 200 unimpeded. Insome embodiments the ablation element transmits at least approximately20% of the light through said element to the skin. In more advantageousembodiments the ablation element transmits at least 40% of the light. Inyet more advantageous embodiments the ablation element transmits atleast 70% of the light. The portion of light from the vascular targetinglaser handpiece that impinges on and is absorbed by the chromophorematerial elements 32 serves to heat said material. In this manner theablation element serves to produce an array of hot spots on the contactwindow 33 that will ablate spots on the surface of the skin 200. Inadvantageous embodiments, the chromophore material elements 32 will beheated to a temperature of at least approximately 100° C. by thevascular targeting laser light impinging on said elements.

It has been found that the ablation element substrate 31 may be made ofa material with relatively low thermal conductivity, such as silica orquartz, and the contact window 33 made of material with high thermalconductivity, such as sapphire. In this way, heat is transferredefficiently to the skin, rather than diffusing into the substrate 31. Inadvantageous embodiments, the contact window 33 has a thickness that isless than the distance between chromophore material elements 32, tominimize lateral heat diffusion in the contact window 33.

FIG. 21 shows that small holes can be created in fused silica, in the100 μm to 500 μm size range, or larger. These holes are then filled witha chromophore material, for example amorphous carbon or iron oxide. Anadvantageous aspect of the ablation element is that the chromophore isnot in contact with the skin. The ablation element can be cleaned andreused.

In some advantageous embodiments, the vascular targeting treatmentincludes an ablation element and application of a topical anesthetic.Light from the vascular laser with ablation element is applied to theskin, and has two effects: (1) the vascular laser light damages themicrovasculature of the skin tumor leading to tumor cell injury anddeath, and (2) modification of skin permeability by coagulation ofdermal microvasculature and production of ablations in the epidermisserves to increase the exposure of dermal tissue to applied drugs.Effect (2) was described in WO/2010/102099A1 Method and Apparatus forCancer Therapy, Application of the vascular laser treatment before thethermal laser has the advantage that with the modification of dermalpermeability to topical drugs, the procedure can be used to eitheranesthetize the skin prior to the thermal laser treatment, to expose thedermis in the vicinity or the skin tumor to anticancer drugs, or both.

In advantageous embodiments, when vascular laser irradiation is used,the time between vascular laser irradiation and topical drug applicationis sufficient for purpura to form from the vascular laser treatment, orat least approximately 10 min. Purpura is indicate of a reduction indermal permeability to topically applied anesthetic or anticancer drug,such that dermal exposure to said drug is increased. Also, becauseerythema indicative of increased blood flow is a common acute effect ofvascular laser irradiation, the time between vascular laser irradiationand topical drug application is sufficient for the erythema to subside,or approximately 20 min.

FIG. 22 shows an example of an embodiment of the present invention. Theapparatus 100 includes two light sources: a vascular treatment device150 (for example, a pulsed dye laser, a KTP laser, or a intense pulsedlight source (IPL)), and a thermal therapy laser device 120. Devices 150and 120 have light output ports 150 a and 120 a, respectively, forcoupling of optical fibers to the respective handpieces. The thermaltherapy laser has a controller 110 that takes signals from the leads 11of temperature sensors 10 of the detachable grid element 9 of thethermal therapy laser handpiece 1 and monitors accumulating damage indermal collagen and tumor cells during thermal therapy, providinginformation on this accumulating damage to the operator via a display110 a, indicators, and/or alarms. This allows the operator to controlthe thermal therapy treatment process so that substantial tumor celldeath occurs without substantial damage to normal dermis. The vasculartreatment device has a handpiece 20 that may have an ablation element30, as described in WO/2010/102099A1, to increase permeability of atopical agent applied to the skin. The apparatus may also comprise acooling system 130, for cooling the windows of the thermal therapyhandpiece and/or the ablation element of the vascular handpiece. Coolantlines 15 a and 15 b of the vascular handpiece, and coolant lines 12 aand 12 b of the thermal therapy handpiece may be connected to coolingsystem 130.

Another treatment schema is shown in FIG. 23, for treatment according tothe invention with thermal therapy, vascular targeting, and a topicalanesthetic agent. In this schema, vascular laser irradiation of a skintumor is followed by application of topical anesthetic to the tumor siteon the skin. In some advantageous embodiments, an ablation elementattached to the vascular laser handpiece produces an array of ablationsin at least the stratum corneum of the epidermis of the skin tumor siteduring vascular laser irradiation, said ablations increasing thepermeability of the epidermis. The topical agent is applied immediatelyafter irradiation when the vascular handpiece is removed from the skinsurface, or, in some embodiments, after the formation of purpura at theirradiation site. In purpuric skin, dermal permeability is reduced dueto a reduction in blood uptake of anesthetic drug, to increase dermaldrug exposure and reduce possibly deleterious systemic uptake of thedrug. The thermal laser irradiation is applied after the anesthetic drughas been on the skin for a sufficient time to produce numbing of thetreatment site, at which time the topical drug is removed from the skin.Thermal laser irradiation is applied to the purpuric skin withmonitoring of temperature and damage Ω, and in advantageous embodimentsincludes skin cooling. Temperature at the location of each sensor needleis monitored to ensure that the tumor cells have been exposed to athermal history that corresponds to a large damage integral Ω, forexample a Ω of at least approximately 2, and more advantageously greaterthan 2, for tumor cells, and, secondly, that the damage integral Ω fornormal dermal collagen that is less than approximately 1.5 at thelocation of each sensor needle. A topical anticancer drug is appliedimmediately after thermal laser irradiation, covered with a dressing,and is allowed to remain on the skin to achieve therapeutic exposure atthe tumor site. In advantageous embodiments, the topical anticancer drugremains on the skin at the tumor treatment site for a period of at leastone hour, more advantageously at least about 4 hours, and moreadvantageously at least about 8 hours or overnight, at which time thedressing is removed and the drug washed off. In embodiments of theinvention depicted in the schema of FIG. 23, highly effective andselective tumor treatment is achieved with a combination of indirecttumor cell killing by hypoxia induced by vascular targeting, directthermal injury to tumor cells by thermal laser irradiation, and directtumor cell killing by the cytotoxic or anticancer drug, with aconcomitant reduction in pain from the thermal laser irradiation.

The relevant teachings of all patents, published applications andreferences cited herein are incorporated by reference in their entirety.

While this invention has been particularly shown and described withreferences to example embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

What is claimed is:
 1. An apparatus for treatment of soft tissue,comprising: a source of radiation; a handpiece which is adapted totransmit radiation emitted from the source of radiation to a region ofsoft tissue, said handpiece adapted to be positioned adjacent to or incontact with said soft tissue region; a grid element, having a singletemperature sensor, the grid element adapted to hold the singletemperature sensor at a particular location in contact with or embeddedin said region of soft tissue, the single temperature sensor producing asingle temperature signal for a duration of a time interval; and amicroprocessor configured to calculate two different cumulative measuresof potential tissue damage at the particular location of the singletemperature sensor, the two different cumulative measures of potentialtissue damage both calculated using the single temperature signal fromthe single temperature sensor for the duration of the time interval, themicroprocessor further configured to calculate a first measure of thetwo different cumulative measures of potential tissue damage as a firstfunction of the single temperature signal for the duration of the timeinterval, the first measure indicative of damage for a normal tissuecomponent potentially present in the region of soft tissue, and themicroprocessor further configured to calculate a second measure of thetwo different cumulative measures of potential tissue damage as a secondfunction of the single temperature signal for the duration of the timeinterval, the second function different from the first function, thesecond measure indicative of damage for a malignant, hypertrophic, ordiseased component potentially present in the region of soft tissue. 2.The apparatus of claim 1, wherein the source of radiation is a coherentor incoherent source operating in a range of between 700 nm and 1310 nm.3. The apparatus of claim 1, wherein the grid element is attached to thehandpiece.
 4. The apparatus of claim 1, wherein the temperature sensorcomprises a thermocouple or thermistor.
 5. The apparatus of claim 4,wherein the thermocouple or thermistor is contained within a needlehaving a proximal end and a distal end, such that the proximal end isaffixed to the grid element and the distal end is embedded in the regionof soft tissue.
 6. The apparatus of claim 1, wherein the normal tissuecomponent is collagen.
 7. The apparatus of claim 1, wherein themalignant, hypertrophic, or diseased component is tumor cells.
 8. Theapparatus of claim 1, wherein the normal tissue component is dermalcollagen, and the at least one malignant, hypertrophic, or diseasedcomponent is skin cancer cells.
 9. The apparatus of claim 1, wherein atleast one of the two different cumulative measures of potential tissuedamage is an Arrhenius damage integral.
 10. The apparatus of claim 1,wherein the handpiece comprises a cooling element for cooling the regionof soft tissue for at least a portion of the time that the temperaturesensor is in contact with or embedded in said soft tissue.
 11. Theapparatus of claim 1, further comprising a display unit, whereby atleast one of the two different cumulative measures of potential tissuedamage is displayed for at least a portion of the time that thetemperature sensor is in contact with or embedded in said soft tissue.12. The apparatus of claim 1, wherein the grid element is adapted tohold at least two temperature sensors embedded at least two differentdepths in the irradiated soft tissue, one of the at least twotemperature sensors being the single temperature sensor at theparticular location in contact with or embedded in the region of softtissue.
 13. The apparatus of claim 1, wherein the microprocessor isfurther configured to calculate the two cumulative different measures ofpotential tissue damage at least one of before transmission of theradiation or after transmission of the radiation.
 14. The apparatus ofclaim 1, wherein the single temperature sensor at the particularlocation is a first temperature sensor, and wherein the grid element isfurther adapted to hold one or more second temperature sensors at one ormore respective locations different from the particular location.